An effective heat propagation path-based online adaptive thermal model for IGBT modules

The information of junction temperature is crucial for operation management of IGBT modules. In practice, junction temperature is typically estimated by using an electrothermal model. IGBT modules are subject to various aging processes during operation, some of which, e.g. substrate solder crack, changes the thermal impedance of an IGBT module. However, in the literature little work has included the aging effects into online thermal behavior modeling of IGBT modules. This paper proposes an Effective Heat Propagation Path (EHPP)-based online adaptive thermal model for IGBT modules, where the EHPP is proposed to quantify the impact of substrate solder cracks on the heat propagation inside the IGBT modules. A straightforward relationship between substrate solder crack and the degree of nonuniformity of case temperature distribution is established. Based on the EHPP, the parameters of a thermal network, e.g., a Cauer thermal network, are adjusted online to track the thermal behavior changes of the IGBT modules caused by substrate solder cracks, leading to an adaptive thermal model. The proposed adaptive thermal model is validated by comparing with finite element analysis (FEA) simulation results for a commercial IGBT module.